Variables, Triggers and the Back button

[jcamps]

Hi,

In my QVW, I'm using a trigger event to change the value of a variable when the selection changes. So, when I make a selection, the event triggers and the variable changes. So far, so good. My problem is with the back button: the first time I click on BACK the variable rolls back, and I need a second "Back" click to undo the original variable. This is not acceptable since the variable value is related to the selection, and a single "back" leaves an incorrect state.

A simple attached xample might help:

     - field MYFIELD, values 1,2,3

     - variable MYVAR

     - Objects: MYFIELD Listbox, and MYVAR Textbox.

There is a ONSELECT trigger on Myfield, that sets MyVar as "=10*Myfield".

First, select "1" on MyField. the event triggers and sets the MyVar as 10*1... so the TextBox displays "10".

Repeat with "2", same logic and the TextBox displays "20".

So far, so good.

BUT, if I click "back", the VAR is rolled back to "10" BUT NOT the Field. This results in having on-screen the value "2" still selected, but the textbox displays "10"..... obviously, not 10 times the selected value

I dont know how to avoid the "variable change" being inserted in the "back pile". Any other workaround would be also apreciated.

Note that I know i could set MyVar directly as an expression so that it evaluates automatically, without a trigger. The problem is, this formula is very complex, and the same value is used over 50 times in a single sheet. For some reason QV does not cache the result, so it is evaluated 20 times in a single tab making the sheet unusable.

[hoodhill]

Hi.

I don't see why you're using a trigger in this instance, why not just set the MyVar variable to '= MyField * 10'. You can then get rid of the trigger and once done the back button works (as it's backing out the last change).

[jcamps]

This was just a simple example...

Real use scenario would be, I have a large set of selections in a tab. Some are on screen (most common, like "YearMonth" or "Brand"), others appear / popup on demand when user clicks on "More selections" (more rarely used, say "YearWeek"). What I do, create the "popup" objects with visibility based on a variable, say vPopupEnabled, plus a button that switches that variable back and forth between 1 and zero.

What the user does (just an example)

* Select in YearMonth

* ...

* Click on "Open selections"

* Select on YearWeek

* Click on "Close selections"

* Click on "Open selections"

* Change YearWeek

* Click on "Close selections"

* Switch to a different TAB where there are no popup selections

* Select on Brand

Now, if the user clicks on "Back", he'd expect to navigate back his selections. What he sees is as he clicks on "back":

1. OK, remove selection on Brand
2. Does nothing (!!)
3. Back on YearWeek
4. Nothing again (!?!)
5. Nothing again (@#@!!)
6. Mmmmm, WTF... let me switck back to the other tab. Oh well, what's the popup doing open now?

Hope that's clearer...

[jerrysvensson]

We use the extension HideIt and remove the Back/Forward/Clear buttons. Problem solved in Ajax.